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埃洛石纳米管管壁结构的调控及其重金属离子吸附性能

Regulation of Halloysite Nanotube Wall Structure and Their Adsorption Performance of Heavy Metal Ions

【作者】 张杰

【导师】 傅梁杰;

【作者基本信息】 中南大学 , 材料科学与工程, 2022, 硕士

【摘要】 我国黏土矿物储量丰富、应用范围广泛,但在世界产业链中仍以出口原料为主。埃洛石是一种重要的黏土矿物,有着独特的中空管状结构和丰富的表面羟基,其在环境、催化、生物等领域的高值化应用一直是国内外的研究热点。然而,天然埃洛石纳米管的管径大小、孔容装载量、表面吸附性能等指标,是制约埃洛石性能进一步提升的难点。埃洛石管中含有的伴生杂质,堵住了其内腔。这种现象极大限制了埃洛石的负载能力,甚至使活性因子不能进入内腔。基于此,本论文对埃洛石管壁结构进行管内除杂和粒度分级,然后用冷冻/融化循环法扩大埃洛石的孔体积,并制备了埃洛石基铅吸附材料。针对埃洛石本身管壁结构的调控,本文首次提出一种绿色、无污染并且不破坏埃洛石晶体结构的管壁结构调控新方法,可显著扩大埃洛石纳米管的孔体积和平均孔径,实现埃洛石纳米管管内装载容量的提升。该方法基于高速剪切均化作用及水结冰膨胀作用的原理,对埃洛石纳米管管腔和孔隙的杂质进行了有效迁移(Hal-P),成功实现了对我国多产地埃洛石的管壁结构调控,其中辰溪(CX)、铜陵(TL)的埃洛石的总孔体积Vpore增长率分别为27%、79%。然后对埃洛石扩孔(Hal-P-8E),Hal-P-8E-CX的Vpore增加率为37.02%,而Hal-P-8E-TL的Vpore增加率为170.9%。针对埃洛石在重金属离子吸附领域的高值化应用,本文对埃洛石进行酸浸、钛羟基嫁接改性,在埃洛石纳米管(Hal-A)上嫁接了大量高度分散且富含羟基的Ti(OH)4基团,形成了一种具有超高Pb(Ⅱ)离子吸附容量(1040 mg/g)和极低重金属离子残余量(3.51μg/L)的新型矿物基吸附材料(Hal-A-Ti)。酸浸后的埃洛石表面有很多的羟基官能团和缺陷位点,Ti(OH)4锚定在Hal-A的内壁和外壁上,形成分散的触手结构,增大了接触面积,有效的促进Pb(Ⅱ)离子的选择性吸附。这种材料具有优异的可再生性能、极强的选择性吸附能力、便捷的回收性以及低廉的价格(25083元/吨),并能在极短的时间内达到吸附平衡状态(2 min)。图59幅,表14个,参考文献161篇

【Abstract】 The clay mineral reserves of China are very rich and widely used,but it is still mainly exported as raw materials in the world industrial chain.Halloysite(Hal)is an important clay mineral with a unique hollow tubular structure and abundant surface hydroxyl groups.Its high-value applications in the fields of environment,catalysis,and biology have always been a research hotspot at home and abroad.However,the diameter,pore capacity,and loading capacity of natural halloysite nanotubes,surface adsorption performance,and other indicators have always been the difficulties restricting the further improvement of halloysite performance.There are many accompanying impurities in the tube that block the inner cavity of the halloysite.This phenomenon greatly limits the loading capacity of the halloysite and even prevents the active factor from entering the lumen.Based on this,the tube wall structure of the halloysite is removed and the particle size is classified in this thesis,and then the pore volume of the halloysite is enlarged by the freezing/thawing cycle method.At the same time,halloysite-based lead adsorption materials were also prepared.Aiming at the regulation of the halloysite tube wall structure,a new method for regulating the tube wall structure that is green,pollution-free,and does not destroy the halloysite crystal structure is proposed for the first time.This method can significantly expand the pore volume and average pore size of the halloysite nanotubes and realize the enhancement of the loading capacity in the halloysite nanotubes.This method effectively migrates the impurities in the lumen and pores of halloysite nanotubes through the principle of high-speed shear homogenization and the freeze/thaw cycle,and successfully realizes the regulation of the tube wall structure of halloysite.The total pore volume Vpore of the halloysites from Chenxi and Tongling increased by 27%and 79%respectively.The Vporeincrease rate of Hal-P-8E-CX was 37.02%,while the Vpore increase rate of Hal-P-8E-TL was 170.9%.In view of the high-value application of halloysite in the field of heavy metal ion adsorption,acid leaching and titanium hydroxyl grafting modification were carried out on halloysite in this paper,and a large number of highly dispersed and rich halloysite nanotubes(Hal-A)were grafted on it.The Ti(OH)4 group of the hydroxyl group formed a new mineral-based adsorption material(Hal-A-Ti).There are many hydroxyl functional groups and defect sites on the surface of the halloysite after acid leaching.Ti(OH)4 is anchored on the inner and outer walls of Hal-A to form a dispersed tentacle structure,which increases the contact area and effectively promotes selective adsorption of Pb(Ⅱ)ions.This material has excellent renewable performance,strong selective adsorption capacity,convenient recovery,low price(25083 yuan/ton),and can reach the adsorption equilibrium state in a very short time(2 min).

  • 【网络出版投稿人】 中南大学
  • 【网络出版年期】2024年 02期
  • 【分类号】TB383.1;O647.3
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